US 7394296 B1 Resumen An apparatus and method for automatically offsetting the linear deviation of a V/F converter, the offset adjust pin of which is connected to a fixed resistance, and the frequency output pin of which is connected to a microcontroller unit (MCU) via an opto-isolator, a standard V/F transfer function being pre-stored in the MCU, wherein standard frequencies F
1 and F0 (i.e., two coordination points (V1, F1) and (V0, F0)) are output by the V/F converter, when V1 and V0 are input as standard voltages, and the MCU may detect an error status in the V/F converter, when the V/F converter obtains real output frequencies F1′ and F0′ from real input voltages V1 and V2, and standard coordination points (F1, K1) and (F0, K0) will be corrected to (F1′, K1) and (F0′, K0′), from which a transfer function of offsetting frequency down is obtained, when the MCU processes a frequency down procedure. Reclamaciones(1) a) setting up a standard V/F transfer function and a standard frequency down function, both standard functions having a corresponding relationship between (V
1, F1), (V0, F0) and (F1, K1), (F0, K0);b) inputting a first voltage V
1, thus a real first frequency F1′ being obtained;c) inputting a second voltage V
0, thus a real second frequency F0′ being obtained;d) comparing above two corresponding value sets, namely, F
1′ with F1, and F0′ with F0;e) in step d, if any corresponding values are different, namely, F
1≠F1′ or F0≠F0′, frequency down values K1 and K0 are set correspondingly to F1′ and F0′ respectively;f) according to two coordinate points (F
1′, K1) and (F0′, K0), calculating an offset frequency down function, figure of which is a straight line passing through said two coordinate points in a Cartesian coordinate. Descripción 1. Field of the Invention The present invention generally relates to a V/F converter, in particular, to a V/F converter for power inverter. 2. Description of Prior Art Following the increasing maturity of frequency conversion technology, the application of frequency converter is very popular currently, not only frequently seen in various domestic appliances (e.g., air conditioner, refrigerator, and washing machine), but also applied prevalently in each industrial control. In frequency conversion application, a V/F converter is usually used, such as: TC9400 series manufactured by MICROCHIP Company and ADVFC32 manufactured by ANALOG DEVICE Company, which are all IC products that convert analogical voltage signal into digital frequency signal, such that the digitization of precision control may be processed conveniently. In said V/F converters, the relationship between input voltage and output frequency is a linear transfer function, which implies a direct proportion relationship between these two values. In all these V/F converters of IC products, an offset adjust pin (e.g., the second leg of TC9400 series and the first leg of ADVFC32) is usually arranged and connected to a variable resistance, the adjustment of which may change the slope of said transfer function during frequency conversion procedure, and thus a more accurate corresponding between the frequency output value and the voltage output value may be obtained. However, such offsetting adjustment must be handled one by one through artificial manner, which is very uneconomical in a mass production of frequency converter, because it consumes substantial manpower and time. Furthermore, in the mobile structure of a variable resistance, its accuracy and endurance are all inferior to those of a fixed resistance, so the phenomenon of resistance floating is occurred frequently and also influences the accuracy of V/F conversion. On the other hand, it has been very popular that a microcontroller unit is used in a frequency converter for processing digital control, but the prior frequency converter did not use the microcontroller unit for offsetting the transfer deviation of V/F converter. Therefore, if an existent microcontroller unit is used for automatically offsetting linear deviation of a V/F conversion, not only the cost of manpower and time needed by previously artificial adjustment can be completely saved without additional element cost, but also the unstable problem generated from the usage of variable resistance may be prevented. Regarding aforementioned drawbacks, the present invention is to provide an apparatus and method for automatically offsetting linear deviation of V/F converter, the error of which may be automatically offset by a microcontroller unit (MCU) without artificial operation, thus manufacturing cost being reduced effectively. The present invention is to provide an apparatus and method for automatically offsetting linear deviation of V/F converter, which uses fixed resistance instead of variable resistance, which is more expansive and less stable, thus the lifetime and stability of frequency controller being able to be promoted notably. To achieve the objectives, the invention provides a V/F converter, the offset adjust pin of which is connected to a fixed resistance, and the frequency output pin of which is connected to a microcontroller unit (MCU) via an opto-isolator, a standard V/F transfer function being pre-stored in the MCU, wherein standard frequencies F The features of the invention believed to be novel are set forth with particularity in the appended claims. The invention itself, however, may be best understood by reference to the following detailed description of the invention, which describes an exemplary embodiment of the invention, taken in conjunction with the accompanying drawings, in which: In cooperation with attached drawings, the technical contents and detailed description of the present invention will be as follows. Firstly, please refer The voltage input side In this case, the MCU Therefore, the relationship between the output and input of both V/F converter Step 1 (S1): firstly, a standard V/F transfer function and a standard frequency down transfer function are established in the MCU Step 2 (S2): the first voltage V Step 3 (S3): the second voltage V Step 4 (S4): after receiving the two real frequencies F Step 5 (S5): if any frequency set is different (i.e., F Step 6 (S6): in other words, after two coordinate points (F Step 7 (S7): in step 6 (S6), if F Please refer to Aforementioned description is only preferable embodiment according to the present invention, being not used to limit its executing scope. Any equivalent variation and modification made according to appended claims is all covered by the claims claimed by the present invention. Citas de patentes
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